Missouri Air Conservation Commission approves plan to show EPA that Jefferson County air is cleaner

It's now up to the Environmental Protection Agency to decide if sulfur dioxide levels in Jefferson County have improved since 2013.

Rici Hoffarth | St. Louis Public Radio

Jefferson County is one step closer to attaining the federal clean air standard for sulfur dioxide, a noxious gas that can cause asthma and respiratory illness.

The Missouri Air Conservation Commission on Thursday approved the state's recommendation to the Environmental Protection Agency that the county's sulfur dioxide levels are within the federal limit of 75 parts per billion.

The county exceeded the limit in 2013, largely due to the high amount of emissions from the Doe Run lead smelter in Herculaneum. This prompted the EPA to designate the county as "nonattainment" for sulfur dioxide. But the smelter has closed since, which caused emissions to drop significantly. That led state officials to ask the EPA to change the county's air status to "attainment."

The Missouri Department of Natural Resources' data also measures emissions from prominent sources of sulfur dioxide emissions, including Ameren Missouri's Rush Island Energy Center. The data indicated that levels were well below the limit.

"We're interested in ensuring that the air quality is safe to breathe for our coworkers as well as the citizens of Missouri," said Steve Whitworth, senior director of environmental services at Ameren Missouri. "We'll continue to do our part to make sure that the air quality stays good in the area."

Ken Miller, an environmental scientist at the clinic, also is concerned that the MDNR's plan to change the county's air-quality status to meeting federal standards does little to address emissions coming from the Rush Island Energy Center.

"There's basically nothing in the plan that will ensure that sulfur dioxide levels are safe for people to breathe," Miller said. "If Ameren were to operate at their permitted limit or close to it, you'd probably get widespread nonattainment through the area."

It's now up to the EPA to accept or reject the MDNR's proposal. The agency's final decision may not come for some time, since its recommendation for the county will also involve a public comment period.

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The Missouri Department of Natural Resources has requested the U.S. Environmental Protection Agency upgrade Jefferson County's air quality status, now that levels of sulfur dioxide have dropped below the federal limit.

In 2013, the EPA designated Jefferson County as "nonattainment," or not meeting the federal standard for sulfur dioxide, a gas that produces toxic odors and causes respiratory problems. A monitor near the Doe Run lead smelter in Herculaneum detected sulfur dioxide levels above 200 parts per billion, said Kyra Moore, director of the state's air quality control program. After the smelter closed in 2013, levels have dropped well below the 75 parts per billion limit.

File Photo | Sarah Skiold-Hanlin | St. Louis Public Radio & The Beacon

Story updated Feb. 17 with comment from Ameren Missouri — A federal judge has approved the Sierra Club's request to intervene in a Clean Air Act lawsuit between Ameren Missouri and the Environmental Protection Agency.

Last month, Chief Judge Rodney Sippel ruled in U.S. District Court that Ameren violated the Clean Air Act when it installed boiler equipment at the Rush Island Power Plant in Festus in the late 2000s without acquiring special permits. The new equipment caused the plant to emit more sulfur dioxide emissions, which at high levels can cause asthma and exacerbate respiratory conditions.

Before Sippel held the first meeting Thursday to determine how Ameren should reduce air pollution, the Sierra Club's lawyers filed a motion to intervene, out of concern that the Trump administration could put the case in jeopardy.